UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION IX

The Honorable JaniceK. Brewer 1700 West Washington Street Phoenix, Arizona 85007 Dear Governor Brewer: 75 Hawthorne Street San Francisco, CA 94105-3901


### AUG 1 9 7014 OFFICE OF THE REGIONAL ADMINISTRATOR

Thank you for your recommendation, dated December 10, 2013, ofair quality designations for the 2012 annual fine pariicle National Ambient Air Quality Standard (2012 armual PM2.s NAAQS) throughout Arizona. This letter is to notify you ofthe U
.S. Environmental Protection Agency's (EPA) preliminary response to Arizona's recommendation and to inform you ofour approach for completing the initial area designations for the 2012 annual PM2.s NAAQS. The EPA agrees with your December 10,2013 recommendation
. We have considered the annual PM2.s designation recommendation submitted by Arizona and have reviewed the relevant technical information, including 2011-2013 air quality data. These data do not indicate any violation ofthe 2012 ammal PM2.s NAAQS in Arizona or contribution to any nearby area. Accordingly, the EPA intends to designate the entire state ofArizona as unclassifiable/attainment. The EPA will make its preliminary designation decisions and supporting documentation available to the general public for review and comment. We will be announcing a 30

-day public comment period shortly in the Federal Register
. After considering the additional information we receive, the EPA plans to promulgate final designations for the 2012 annual PM2
.sNAAQS in December of2014. As background, on December 14, 2012, the EPA promulgated a revised primary annual PM2.sNAAQS (78 FR 3086, January 15, 2013)
. In that action, the EPA revised the primary ammal PM2.s standard, strengthening it from 15.0 micrograms per cubic meter ()lg/m3) to 12
.0 )lg/m3 ; retained the existing 24- hour PM2.s standard at 35 )lglm3; retained the existing 24-hour PM10 (coarse particle) standard at 150 )lglm3; and retained the current suite ofsecondary PM standards. The EPA revised the primary annual PM2.s standard based on an integrated assessment ofan extensive body ofnew scientific evidence, which substantially strengthens our body ofknowledge regarding PM2.s-related health effects. The revised primary armual PM2.s standard will provide increased protection for children, older adults, persons with pre-existing heart and lung disease, and other at-risk populations against an an·ay ofPM2 s-related adverse health effects, including premature mortality, increased hospital admissions and emergency department visits, and development and exacerbation ofchronic respiratory disease. The EPA designates an area as "nonattainment" ifit is violating the 2012 annual PM2.s NAAQS or ifit is contributing to a violation ofthe NAAQS in a nearby area. Consistent with designations for previous PM2.s standards, the EPA intends to use a designation category of"unclassifiable/attainment" for areas that are monitoring attainment or do not have monitors, and that the EPA has reason to believe are likely attaimnent and are not contributing to nearby violations
. Additionally, the EPA intends to designate as
Printed on Recycled Paper"unclassifiable" those areas where the EPA cannot determine based on available information whether the area is meeting the NAAQS or where EPAhas not determined that the area contributes to a nearby violation. At this time, the EPA is proceeding with intended initial area designations using qualityassured, certified air quality monitoring data from 2011 to 2013. · The EPA is committed to working with the states and tribes to share the responsibility ofreducing PM2 

### .s air pollution. Current and upcoming federal standards and safeguards- including pollution reduction rules for power plants, vehicles, and fuels

- will ensure steady progress to reduce PM2.s-forming pollution and will protect public health in communities across the country. We look forward to a continued dialogue with you and your staffas we work together to implement the 2012 annual PM2.s NAAQS. Should you have any questions, please contact me, or have your staffcontact Deborah Jordan ofmy staffat 415-947-8715, orjordan.deborah@epa.gov. Sincerely,

cc: Hemy R. Darwin, Director, Arizona Department ofEnvironmental Quality (via email) Eric Massey, Director, Air Quality Division, Arizona Department of Environmental Quality